Cryosurgery is the therapeutic application of cold, a “controlled frostbite.” Many different cryogens have been used. Liquid nitrogen, at a temperature of -195.8°C (-320.4°F), is the most common. Cryosurgery effectively treats many superficial lesions, such as actinic keratoses, lentigines, molluscum contagiosum, seborrheic keratoses, and warts. Deeper, malignant lesions such as basal cell carcinoma are also treated with cryotherapy, but this requires special equipment and expertise and is not as successful as other methods.

Cryosurgery causes intracellular and extracellular ice crystal formation, alterations in tissue, and vascular stasis. These changes lead to tissue anoxia and necrosis. Melanocytes are most easily destroyed by cryosurgery. This means that hypopigmentation can be a permanent complication of therapy, especially in dark-skinned patients. However, lentigines, for example, can be eliminated without harming the keratinocytes or dermis. Moreover, because fibroblasts are relatively insensitive to cold, scarring rarely follows the treatment of superficial lesions.